Spatially extended charge density wave switching by nanoscale local manipulation in a VTe 2 monolayer
Résumé
Monolayer transition metal dichalcogenide VTe 2 exhibits multiple charge density wave (CDW) phases, mainly (4 × 4) and (4 × 1). Here we report a facile dynamic and tens-of-nanometer scale switching between these CDW phases with gentle bias pulses in scanning tunneling microscopy (STM). Purposely bias pulses stimulate reversible random CDW symmetry change between the isotropic (4 × 4) and anisotropic (4 × 1) CDWs, as well as CDW phase slips and rotation. The switching threshold of ∼1.0 V is bias-polarity independent and the switching rate varies linearly with the tunneling current. Density Functional Theory (DFT) calculations indicate a coherent CDW phase switching incurs an energy barrier of ∼2.0-3.0 eV per (4 × 4) unit cell. While being a challenge in understanding the observed large-area CDW random fluttering, we provide some possible explanations. The ability of manipulating electronic CDW phases sheds new lights on tailoring CDW properties on demand.
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